In order to test online updates in openQA the addon= parameter is used on the
kernel command line. Also, use of online repositories need to be enabled during
installation. Going to that dialog from the role selection dialog apparently
resets or ignores the addon parameter. So the specified addon repo doesn't get
used actually.

I'll attach y2logs of an installation up to the user selection. Both have
addon= set. One installation went to the online repo config and the other one
not. Only the latter actually used the addon repo as can be seen from the
dialog to import an untrusted key.